Self-feathering fan



June 24, 1952 5, BELL 2,601,495

SELF-FEATHERING FAN Filed July 17, 1950 wmu.

III/lIIIIIIII/IIIIII INVENTOR. JA/wuz 0. 8514 Patented June 24, 1952 UNITED STATES PATENT OFFICE 3 Claims.

This invention relates generally to cooling fans of the type employed in connection with vehicle propelling engines for cooling purposes and refers more particularly to improvements in fans having blades or vanes which decrease in pitch as the engine speed increases.

It is an object of this invention to provide a cooling fan having a rotatable hub and having a plurality of circumferentially spaced radially outwardly extending vanes or blades supported on the hub by mountings which, although exceptionally simple, nevertheless, assure reducing the pitch of the various blades when the engine speed exceeds a rate where cooling by the fan is no longer required or in any case is substantially reduced. Thus the power required to drive the fan at elevated engine speeds is materially reduced and the operating efliciency of the engine is greatly increased.

The foregoing as well as other objects will be made more apparent as this description proceeds, especially when considered in connection with the accompanying drawing, wherein:

Figure 1 is an elevational view of a cooling fan embodying the features of this invention;

Figure 2 is an enlarged elevational view of a part of the fan shown in Figure 1;

Figure 3 is a view similar to Figur 2 showing the parts in a dififerent position;

Figure 4 is a sectional view taken on the line 4--4 of Figure 2; and

Figure 5 is a sectional view taken on the line 5-5 of Figure 2.

The cooling fan selected herein for the purpose of illustration comprises a hub I0 and a plurality of blades or vanes H. The blades II are spaced from each other circumferentially of the hub I0 and extend generally radially outwardly from the hub Ill. The fan is especially designed for use in connection with an automobile vehicle propelling engine and the hub i0 is designed for attachment to a suitable shaft driven by the engine in the usual manner.

The blades II are formed separately from the hub l0 and are mounted on the hub in a manner such that the pitch of the blades varies in accordance with the magnitude of the forces acting on the blades as a result of rotation of the hub Ill. The principal forces which act on the blades in operation are centrifugal force and the resistance of the atmosphere to the passage of the blades II through it. Generally speaking these forces increase as the speed of the engine or the speed of the hub I0 increases, and act to reduce the pitch of the blades H. The general arrangement is such that at low speeds when the circulation of air due to the movement of the vehicle is at a minimum, the pitch of the blades II is at a maximum so that the full capacity of the fan is available to assist in cooling the engine. On the other hand, as the speed of the engine or hub Ill increases, the pitch of the blades II becomes less; and as a result, the fan consumes less power and creates less :noise at higher speeds.

With the above in view, reference is made more in detail to the specific mounting of the blades II on the hub ID. All of the blades II are supported on the hub H] by identical mountings, and accordingly, a description of one mounting will sufiice for all. As shown in the drawing, a bushing I2 is welded, brazed or otherwise secured to one side of the hub III with its axis extending radially in relation to the hub axis, and a second bushing I3 is similarly secured to the blade II with its axis aligned with the axis of the bushing I2. The bushing I3 is fixed to one side of the blade I l at the bottom of the latter, and is positioned substantially midway between the opposite side edges or the blade I I.

The blade II is held in assembled relation with the hub I0 by a stud I4 which extends freely through the bushings and has a head I5 at the outer end adapted to seat on the adjacent end of the bushing I3. The inner end of the stud I4 extends for some distance below the inner end of the bushing I2 and a collar I6 is secured to the inner end of the stud by a suitable set screw H. A suitable coil spring l8 surrounds the inner end of the stud l 4 between the collar I6 and the inner end of the bushing l2. The coil spring I8 is normally under compression and functions to yieldably hold the adjacent ends of the bushings I2 and I3 in frictional engagement.

It will be noted particularly from Figures 2 and 3 of the drawing that the outer end of the bushing I2 is fashioned with ,a generally V-shaped recess [9, and the lower end of the bushing I3 is formed with a correspondingly shaped projection 20. The V-shaped projection 20 seats in the V-shaped recess I9 and cooperates with the latter in positioning the blade I l at its maximum pitch angle with reference to the plane of rotation of the hub Ill.

It follows from the above that all of the blades I I are normally urged by their respective springs l8 to positions wherein they extend at the maximum pitch angle with respect to the plane of rotation of the hub. The blades ll remain in the above position until the forces acting on the blades as a result of rotation of the hub 10 overcomes the compression load on the springs l8. When this occurs the blades ll rotate in the direction of the arrow A (Figures 2 and 3) about the studs Hi to reduce the pitch of the blades. As the blades I l rotate about the respective axes of the studs 14, the bushings 13 secured to the blades rotate relative to the bushings l2 secured to the hub H], and 'as 'a consequence, the sides 2! of the 'V-shaped projections ride outwardly on the adjacent sides 22 of the V-shaped recesses [9. If desired these sides may be curved slightly to provide a camming effect and facilitate rocking of the blades. In any case the blades H are displaced outwardly along the respective studs 54 as they rotate about the latter and the springs 13 are further compressed. Thus the springs 18 in conjunction with the angle of inclination of the V-shaped sides 2| and 22 determine'the speed of the engine orhub Ill at which the pitch of the blades II is reduced, and any desired operating characteristic maybeprovided'by changing the angle of inclination o'f'thesides 2| and 22, and/or varying the compressive load on the springs; or

by employing springs of different strength. The

V-shap'ed projections and recesses also coact to vguidemovement of th'e blades ll relative to the hub and assure quiet operation of the fan.

What I claim as my invention is: 1. ma cooling fan, a rotatable hub, a vane extending outwardly from the vhub and rotatable as a unit with the hub, a bushing secured to the 'hub with its axis extending generally radially with respect to the hub axis, a second bushing 3o secured to the vane in alignment with the first bushing, a pivot pin extending through said bushings and having stops at opposite ends, the adjacent ends of the bushings having engaging surfaces inclined relative to the axis of the pivot pin in directions to move the vane outwardly along said pin in response to the forces acting on the vane as a result of rotation of the hub, and a spring surrounding the pin and held under compression between the stop at the inner end of the pin and the adjacent end of said first bushing.

-2. Theic'ooling fan set forth in claim 1 in which one bushing has a generally V-shaped projection on the end adjacent the other bushing and the latter has a correspondingly shaped recess for receiving said projection.

v-3. The'cooling fan set forth in claim 2 in which the projection and recess cooperate with one another and-With said spring to yieldably hold the vane in aposition wherein it extends at the maximum pitch angle relative tothe hub.

SAMUEL D. BELL.

REFERENCES CI'IJED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1 449585 Luther Mar. 27, 1923 1,685,323 Hansen Sept. '25, 1928 2,118,928 Kissel May 31, 1938 2,415,421 De Filippis Feb. 11, 1947 FOREIGN PATENTS Number Country Date 680,813 "Germany Sept. '7, 1939 

